Steel for tools operating at elevated temperatures



Patentecl Nov. 27, 2951 1 STEEIlF OR 'rooLs OPERATING A ELEVATEDTEMPERATURES Helmut Krainer, Kapfenberg'fliustria, assignor to Gebr.Biihler, & Co. 'Aktiengesellschaft,

- Vienna, Austria No Drawing. Application February 27,1948; Se- 1 rialNo. 11,873. .In Germany March 12, 1941 l Section 1 Public Law69!),Aug1ist s, 1946 Patent expires March 12, 1961 The use of alloysteel containing tungsten, chromium, molybdenum and vanadium for toolsoperating at elevated temperatures is commonly known. Steel containing2.5% chromium, 9% tungsten and 0.5% vanadium has been used mostly. Incases where the above type of steel is used for high duty tools thetotal of the alloying element tungsten, molybdenum and vanadium amountsalways to more than 5%, the bulk consisting of metals in short supplyviz. tungsten and molybdenum.

Hence effort has been made to develop alloy suitable for high duty toolsintended for operation at elevated temperatures havin a restrictedcontent of tungsten and molybdenum. Their performance was, however,found to be considered poorer even in the case of insignificantreductions of the amounts of alloying metals added.

These alloy-saving materials comprise the chromium, molybdenum, tungstenand vanadium alloyed steel with even lower percentage of alloying metalsas compared with those concerned by present invention.

Extended experients have proved the possibility of obtaining not onlyequal performance of the tools but even better efiiciency in comparisonto the well known 9% tungsten steel by suitable adjustment of thealloying elements tungsten, molybdenum and vanadium.

The composition of such alloys has to be within the range of 0.1-0.6%carbon, 0.5-2.0% chromium, 0.5-2% vanadium, 0.3-1.8% tungsten or0.2-l.7% molybdenum, totaling not more than 2%. The percentage oftungsten plus molybdenum should not be less than half the vanadiumpercentage, at the same time not exceeding the 1.5-fo1d value of thevanadium content. The percentage of vanadium about equalling the totalof tungsten plus molybdenum has been found especially advantageous.Tungsten or molybdenum alone may equally be used. The best results,however, are obtained by simultaneous alloying with about the sameamounts of tungsten and molybdenum totallin approximately half thepercentage of vanadium. The respective content of chromium is preferablychosen slightly exceeding the percentage of vanadium. The total oftungsten and vanadium present may, however, exceed the content ofchromium.

Bearing in mind the above balance of the alloying element it is possibleto produce steel with a considerably reduced consumption of alloyingadditions having a better performance as compared With the commonlyknown 9% tungsten alloyed steel.

5 Claims. (01. is- 126) Compositions within the following ranges haveproved to be of special advantage for the use claimed by the presentapplication. 0.2-0.6% carbon, 12% chromium, 0.6-1.4% vanadium, 0.3-0.7%tungsten and 0.3-0.7% molybdenum. Steel containing 0.47% carbon, 1.58%chromium, 0.88% vanadium, 0.48% tungsten and 0.42% molybdenum may bequoted as an example.

Dies for pressing of screws made of the latter steel were compared to acommonly used steel containing 2.5% chromium, 9% tungsten and 0.5%vanadium. Dies made from the steel cited above proved to be of threetimes as good performance as compared with a standard steel. Furtherimprovement of the performance of the dies was obtained when 0.l-0.7% oftitanium were added to steel described in the present invention. Thissurprising success could by no means be expected from the generallyaccepted effects of the alloying elements and was to be obtained solelyby the mutual balance of the respective alloying elements discovered.

Considerable chromium and vanadium as domestic or easily obtainablealloying elements and bearing in mind the three-fold improvement of theperformance as compared to the commonly known and hitherto used steelwith 2.5% chromium, 9% tungsten and 0.5% vanadium, the reduced amountneeded of the metals in short supply, tungsten and molybdenum is ofconsiderable importance.

By the application of steel according to the present invention theconsumption of tungsten and molybdenum is reduced by about 30 timesprovided the same performance is used as a basis of comparison.

The considerable technical progress involved is accentuated by theadvantages both in engineering and economy resulting from the 3-foldlife of the tools.

Iclaim:

1. A steel alloy for making hot-working tools, especially hot-workingpressing dies, consisting essentially of 0.1% to 0.5% carbon; 0.5% to 2%chromium; 0.5% to 2% vanadium; 0.3% to 1.8% tungsten; 0.2% to 1.7%molybdenum; the total percentage of the tungsten and molybdenum contentsnot exceeding 2%; the remainder iron and incidental impurities.

2. A steel alloy for making hot-working tools, especially hot-workingpressing dies, consisting essentially of 0.1% to 0.5% carbon; 0.5 to 2%chromium; 0.5% to 2% vanadium; 0.3% to 1.8% tungsten; 0.2% to 1.7%molybdenum: the total percentage of the tungsten and molybdenumconespecially hot-working pressing dies," consisting 3 r tents lying inthe range from 0.5 times to 1.5 times the percentage of vanadium; theremainder iron and incidental impurities. I

3. A steel all'ny for. making hot+iworking tools;

essentially of 0.2% to 0.5% carbon:- 1% tc-2% lF chromium; 0.6% to 1.4%vanadium 0.3% to...

0.7% tungsten; 0.3% to 0.7% molybdenum; the... ,3 remaindersubstantially all iron and incidental 7 ,4 impurities. 2118;78231 5. Thecomposition defined in claim 1 having an additional content of 0.1% to0.7% of titanium.

, HELMUT .K AmER.

REFERENCESUITED The following references are of record in the file ofthis patent: V

' UNITED STATES PATENTS Name Date 7 Braid; Apr. 17, 1934 RIoyen Jan. 14,1936 FOREIGN PATENTS f 1Country Date Great Britain 1 Apr. 28, 1932 GreatBritain June 7, 1934 Germany Mar. 22, 1939 Switzerland May 16, 1940

1. A STEEL ALLOY FOR MAKING HOT-WORKING TOOLS, ESPECIALLY HOT-WORKINGPRESSING DIES, CONSISTING ESSENTIALLY OF 0.1% TO 0.5% CARBON; 0.5% TO 2%CHROMIUM; 0.5% TO 2% VANADIUM; 0.3% TO 1.8% TUNGSTEN; 0.2% TO 1.7%MOLYBDENUM; THE TOTAL PERCENTAGE OF THE TUNGSTEN AND MOLYBDENUM CONTENTSNOT EXCEEDING 2%; THE REMAINDER IRON AND INCIDENTAL IMPURITIES.